Every day the US Marshals Service locks up 60,000 federal pretrial (and presumed innocent) detainees. The Marshals detain more people than ICE and more than the pretrial detention systems in all but two states. The population is swelling from Trump’s "zero-tolerance" immigration policy. Despite its size, the system has never been deeply scrutinized, in part because the agency doesn’t own or operate its own jails; instead, it contracts with county jails and private prisons. As this investigation reveals, these federal detainees are locked up in failing and dangerously unsafe jails, hundreds of detainees have died inside, and the Marshals have refused to impose oversight or accountability.